1. Technical Field
The present invention relates to a room-temperature-curable organopolysiloxane composition and to a method for its preparation. More specifically, the present invention relates to a room-temperature-curable organopolysiloxane composition that exhibits tack during the course of its cure and that forms a cured product strongly adherent to a variety of substrates when cured while in contact with substrate. The present invention also relates to a method for the preparation of this composition.
2. Prior Art
Many room-temperature-curable organopolysiloxane compositions can be stored for long periods of time in the absence of moisture and cure at room temperature in the presence of moisture. Moreover, when cured while in contact with asubstrate, they form a cured product that adheres to a variety of substrates. As a result of these attributes, they are used as adhesives, sealants, and coatings in construction and industry, for electrical and electronic instruments and devices, and so forth.
Such room-temperature-curable organopolysiloxane compositions are exemplified by the following:
(i) a room-temperature-curable organopolysiloxane composition comprised of organopolysiloxane that contains at least 2 silicon-bonded alkoxy groups in each molecule, surface-treated silica, alkoxysilane or partial hydrolysis condensate thereof, and titanium chelate catalyst as shown by Japanese Patent Application Laid Open [Kokai or Unexamined] Number Sho 61-247756 [247,756/1986], published November 5, 1986; PA1 (ii) a room-temperature-curable organopolysiloxane composition comprised of organopolysiloxane that contains at least 2 trialkoxysilyl groups in each molecule, surface-treated silica, alkoxysilane or partial hydrolysis condensate thereof, and titanium chelate catalyst as shown by Japanese Patent Application Laid Open Number Sho 62-252456 [252,456/1987], published Nov. 4, 1987; and PA1 (iii) a room-temperature-curable organopolysiloxane composition comprised of polydiorganosiloxane endblocked at both molecular chain terminals with the alkoxysilylethyl group, surface-treated reinforcing filler, alkoxysilane, and titanium catalyst as shown by Lee et al in U.S. Pat. No. 4,711,928, issued Dec. 8, 1986. PA1 (iv) a curable organopolysiloxane composition comprised of the combination of a room-temperature-curable organopolysiloxane composition comprising a silanol-endblocked organopolysiloxane plus organotriacetoxysilane and a free radical reaction-curing organopolysiloxane composition comprising an organopolysiloxane plus an organoperoxide as shown by Przybyla in U.S. Pat. No. 4,034,140, issued Jul. 5, 1977, and PA1 (v) a room-temperature-curable organopolysiloxane composition comprised of silanol-endblocked polydiorganosiloxane, amidosilane, and organoperoxide as shown by Homan et al in U.S. Pat. No. 4,614,760, issued Sep. 30, 1986. PA1 (A) 100 weight parts organopolysiloxane that contains at least 2 silicon-bonded alkoxy groups in each molecule and that has a viscosity at 25.degree. C. of 0.02 to 1,000 Pa.s, PA1 (B) 0.1 to 20 weight parts alkoxysilane with the following general formula or partial hydrolysis condensate thereof EQU R.sup.1.sub.a Si(OR.sup.2).sub.(4-a) PA1 R.sup.1 is a monovalent hydrocarbon group; R.sup.2 is a monovalent hydrocarbon group or an alkoxy-substituted monovalent hydrocarbon group; and a is zero, 1, or 2, PA1 (C) 0.01 to 20 weight parts condensation-reaction catalyst, and PA1 (D) 1 to 1,000 weight parts thickening material, present in the components as described above and derived from an addition reaction-crosslinking organopolysiloxane composition or a free radical reaction-crosslinking organopolysiloxane composition. PA1 (A) 100 weight parts organopolysiloxane that contains at least 2 silicon-bonded alkoxy groups in each molecule and that has a viscosity at 25.degree. C. of 0.02 to 1,000 Pa.s; PA1 (B) 0.1 to 20 weight parts alkoxysilane with the following general formula or partial hydrolysis condensate thereof EQU R.sup.1.sub.a Si(OR.sup.2).sub.(4-a) PA1 R.sup.1 is a monovalent hydrocarbon group; R.sup.2 is a monovalent hydrocarbon group or an alkoxy-substituted monovalent hydrocarbon group; and a is zero, 1, or 2; PA1 (C) 0.01 to 20 weight parts condensation-reaction catalyst; and PA1 (D') 1 to 1,000 weight parts addition reaction-crosslinking organopolysiloxane composition comprising the following components (a) through (c) PA1 (A) 100 weight parts organopolysiloxane that contains at least 2 silicon-bonded alkoxy groups in each molecule and that has a viscosity at 25.degree. C. of 0.02 to 1,000 Pa.s; PA1 (B) 0.1 to 20 weight parts alkoxysilane with the following general formula or partial hydrolysis condensate thereof EQU R.sup.1.sub.a Si(OR.sup.2).sub.(4-a) PA1 R.sup.1 is a monovalent hydrocarbon group; R.sup.2 is a monovalent hydrocarbon group or alkoxy-substituted hydrocarbon group; and a is zero, 1, or 2; PA1 (C) 0.01 to 20 weight parts condensation-reaction catalyst; and PA1 (D") 1 to 1,000 weight parts free radical reaction-crosslinking organopolysiloxane composition comprising the following components (d) and (e)
The following are exemplary of attempts at improving the adherence of room-temperature-curable organopolysiloxane and the physical properties of the cured product:
However, these room-temperature-curable organopolysiloxane compositions cure from the section in contact with atmospheric moisture. Due to this, when such compositions are used to bond adherends, transport or other handling of the bonded assembly prepared from the adherends can cause slippage or displacements in the bonding position of the adherends, as well as, delamination. As a result, in order to prevent slippage or delamination due to transport or other handling of the bonded assembly, there is demand for a room-temperature-curable organopolysiloxane composition that exhibits tack during the course of its cure. This demand is particularly strong with regard to the continuous bonding of electrical or electronic components to substrates.